Immobilized protein films for assessing surface proteolysis kinetics

Area of Science:

• Biochemistry
• Materials Science
• Surface Science

Background:

• Enzymatic cleavage of protein substrates on surfaces is crucial for industries like food, detergents, and biomedicine.
• Existing methods for creating protein substrates often lack reproducibility, uniformity, and stability, hindering accurate surface proteolysis studies.

Purpose of the Study:

• To develop a reproducible, immobilized, multilayer protein substrate for studying surface proteolysis.
• To create a stable and uniform protein film that can be tailored for specific proteolysis susceptibility.

Main Methods:

• A 100-nm ovalbumin protein film was spin-cast onto an amine-functionalized silicon wafer.
• Chemical cross-linking with glutaraldehyde formed a stable multilayer film.
• Ellipsometry and atomic force microscopy (AFM) were used to analyze film thickness, homogeneity, and enzyme cleavage.

Main Results:

• The immobilized multilayer protein substrate demonstrated stability in the presence of detergents.
• Ellipsometry showed a linear decrease in film thickness during protease cleavage, indicating depth-homogeneity.
• AFM confirmed lateral homogeneity and uniform areal surface cleavage by the protease subtilisin Carlsberg.

Conclusions:

• The developed method provides a reproducible and stable multilayer protein substrate for surface proteolysis research.
• This model substrate allows for tailored susceptibility to proteolysis and uniform enzyme action.
• The findings support advancements in understanding and engineering enzymatic surface interactions for various applications.